Existing light base and transformer housings which are used to house isolation transformers and also as mounting bases for in pavement airport navigational lights are usually in the form of cylindrical housings. The bottom end of such a cylindrical housing is closed and the cylinder wall is provided with openings for electrical conduit. The open end of the housing is provided with a flange which is open in its center and allows access to the inside of the cylindrical enclosure as well as provides a mounting surface that spacers, shims and ultimately a light fixture can be attached to. The flange has multiple bolt holes which permit the spacers, shims and light fixture to be threadedly fastened thereto. The existing process for installing such a light base and transformer housing involved placing the housing with the closed end down on compacted earth. A circular, protective plywood cover may be placed over the housing. Concrete or a bituminous surfacing material is then poured around the light base and transformer housing as part of the runway construction with the concrete or bituminous covering the top of the housing to a thickness of several inches. The surface material is then removed by cutting out a circular plug directly over the housing and slightly larger than the housing so that a light fixture can be mated and secured to the light base after the isolation transformer has been installed and connected to the wiring which either has been already installed in the conduit or placed there afterwards. Since the light fixture must be mounted to a specific height in relationship with the surface of the runway pavement, spacers and shims of various thickness must be placed on top of the light base between the light base and the light fixture to adjust the height accordingly. In order to do this, the installer must carefully measure the height of the runway above the top of the light base and order the appropriate shims and spacers for each individual housing before the installation can be completed. This results in considerable delay and is an extremely inefficient manner in which to provide the installation.